Food producers in Manjimup in WA's South West fear a planned biomass power plant will pollute the local area and put agricultural production at risk.

The BioMass Action Group, which represents growers, wine makers and community members opposed to the power plant, are urging the State Environment Minister not to grant an extension for the construction of the plant, 10 kilometres south of the township.

The project missed a March 2014 deadline but the Environmental Protection Authority has recommended the 40 megawatt wood-fired plant be given a further five years to get underway.

The BioMass Action Group believes the project will hurt the clean image of Manjimup agriculture.

Spokesman Neil Bartholomaeus said the South West food bowl will be damaged.

"This area is prime agricultural land and should never be a location which is going to burn 380,000 tonnes of wood a year, which is going to have uncertain results in terms of pollution," he said.

Mr Bartholomaeus is also concerned the region's famed truffles, celebrated in a major annual food and wine festival, will be put at risk.

The Shire of Manjimup has previously said it is confident the plant will go ahead.

A spokesperson for Environment Minister Albert Jacob said the Minister had received the EPA's recommendation.

"Under the Environmental Protection Act, the Minister must now consult with other WA ministers before making a final decision, which he will do in due course," they said.